“Reduction of Multi-Dimensional D’Alembert Equations to Two-Dimensional Equations: Ansatzes, Compatibility of the Reduction Conditions, Reduced Equations”. Transactions of Institute of Mathematics, the NAS of Ukraine 3, no. 2 (November 14, 2006): 98–112. Accessed September 14, 2026. https://trim.imath.kiev.ua/index.php/trim/article/view/385.